Generally speaking the 49/52 series came with the .325 X 8 setup. However the 52/52E and 521E frequently got changed to the 3/8 X 7 or 8 pin. Usually this was because they were limbing saws working along side a 621 or 70E felling saws running 3/8. This kept the files needed to carry to just one. The 49 could pull a 3/8 but was always happier running .325 X 8. Over the years and many of these 49SP saws I've acquired, many more burnt up ones were running 3/8 chains rather than .325. Most came with spur drive stock. I've changed every one out to rim drive. The only saw in the herd still sporting a spur drive is my hardly used 111S and there is a NOS drum with 3/8 and .404 rims for it sitting on the bench, waiting.